In recent years, there has been a need for a size reduction and an energy density increase for power sources for mobile communication devices such as cellular phones and portable personal computers. Under such circumstances, there have been developed nonaqueous electrolytes for lithium ion secondary batteries improved for the purpose of reducing temporal variations in battery characteristics from initial values (improving the discharge capacity). For example, Japanese Patent No. 4423277 (Patent Document 1) discloses a nonaqueous electrolyte for a lithium secondary battery prepared by adding allylboronate ester to a mixed solution obtained by adding a lithium salt to a nonaqueous solvent. Meanwhile, Japanese Patent No. 4154951 (Patent Document 2) discloses a nonaqueous electrolyte for a lithium secondary battery prepared by adding a cyclic siloxane to a mixed solution obtained by adding a lithium salt to a nonaqueous solvent.